Barrier film comprising microfibrillated cellulose and microfibrillated dialdehyde cellulose and a method for manufacturing the barrier film

Abstract

The present invention relates to a method for manufacturing at least one layer of a film wherein the method comprises the steps of; providing a first suspension comprising microfibrillated cellulose, providing a second suspension comprising microfibrillated dialdehyde cellulose, mixing the first suspension with the second suspension to form a mixture, applying said mixture to a substrate to form a fibrous web and drying said web to form at least one layer of said film. The present invention further relates to a film comprising said at least one layer.

The invention claimed is: 
     
       1. A film comprising microfibrillated cellulose wherein the film has an oxygen transmission rate in the range of from 0.1 to 300 cc/m 2 /24h measured according to ASTM D-3985, at a relative humidity of 50% at 23° C. and/or at a relative humidity of 90% at 38° C., and wherein at least one layer of the film comprises a mixture of microfibrillated cellulose and microfibrillated dialdehyde cellulose. 
     
     
       2. The film as claimed in  claim 1 , wherein the film has a basis weight of less than 50 g/m 2 . 
     
     
       3. The film as claimed in  claim 1 , wherein said film is a multilayer film comprising more than one layer. 
     
     
       4. The film as claimed in  claim 1 , wherein said film is a multilayer film and wherein at least one layer of the film is a water vapor barrier film comprising any one of polyethylene (PE), polypropylene (PP), polyamide, polyethylene terephthalate (PET) or ethylene vinyl alcohol (EVOH). 
     
     
       5. The film according to  claim 4 , wherein the water vapor barrier film has a grammage between 10-60 g/m 2 . 
     
     
       6. The film according to  claim 1 , wherein said film is a multilayer film and wherein at least one layer of the film is a metallized barrier layer. 
     
     
       7. The film according to  claim 6 , wherein said metallized barrier layer is a physical vapour deposited metal or metal oxide layer, or a chemical vapour deposited metal or metal oxide layer. 
     
     
       8. The film according to  claim 7 , wherein said metal or metal oxide is selected from the group consisting of aluminium, aluminium oxides, magnesium oxides, silicium oxides, copper, magnesium and silicon. 
     
     
       9. The film according to  claim 6 , wherein said metallized barrier layer has a weight between 50-250 mg/m 2 . 
     
     
       10. A packaging material comprising a base material and at least one layer of the film as claimed in  claim 1 . 
     
     
       11. The packaging material according to  claim 10 , wherein the base material is paper or paperboard. 
     
     
       12. The packaging material according to  claim 11 , wherein the paper or paperboard has a grammage between 20-500 g/m 2 . 
     
     
       13. The packaging material according to  claim 11 , wherein the paper or paperboard has a grammage between 80-400 g/m 2 . 
     
     
       14. The film as claimed in  claim 1 , wherein the film has a basis weight of between 10-50 g/m 2 . 
     
     
       15. The film according to  claim 4 , wherein the water vapor barrier film has a grammage between 30-50 g/m 2 . 
     
     
       16. The film according to  claim 6 , wherein said metallized barrier layer has a weight between 75-150 mg/m 2 .